Other Free Encyclopedias » Medicine Encyclopedia » Genetics in Medicine - Part 3 » Meiosis - Overview, Meiosis I, The Sources Of Genetic Diversity, Meiosis Ii, Chromosomal Aberrations - Comparison with Mitosis

Meiosis - Chromosomal Aberrations

chromosome biology chromosome copies cell

Meiosis is a very intricate process that requires, among other things, the precise alignment of homologous chromosome pairs and correct attachment of microtubules. During meiosis, errors in chromosome distribution may occur and lead to chromosomal aberrations in the offspring. One example is Down syndrome, where affected children carry three copies of chromosome 21 (trisomy 21). This may be explained by the failure of paired chromosomes or sister chromatids to separate in either sperm or egg, leading to the presence of two copies of chromosome 21. After fertilization with a normal gamete, the zygote will carry three copies, which leads to several phenotypic abnormalities, including mental retardation.

Silke Schmidt

Bibliography

Alberts, Bruce, et al. Molecular Biology of the Cell, 3rd ed. New York: Garland Publishing, 1994.

Curtis, Helena, and Susan Barnes. Invitation to Biology, 5th ed. New York: WorthPublishers, 1994.

Raven, Peter H., and George B. Johnson. Biology, 2nd ed. St. Louis, MO: Times Mirror/Mosby College Publishing, 1989.

Robinson, Richard. Biology. Farmington Hills, MI: Macmillan Reference USA, 2001.

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